Thankfully, we can have an idea of the day 1 patch notes through the PS4 Update History, which lists the changes and additions to the new patch. Here is what is included in the day 1 patch.

Version 1.01

Various bug fixes

New items and cutscenes

Cutscene adjustments

Deeper combat, driving and other game mechanics

Saved games must be updated to work with the current version of the game.

Current version saves will not work with the former version of the game.

Judging from the patch notes above, there appears to be quite a lot of changes, even the addition of new cutscenes, which likely refers to Kingsglaive CG scenes being mixed with some of the in-game cutscenes.

As for the other changes, we might hear more details about them directly from the game director, Hajime Tabata, tomorrow.

Final Fantasy XV will be released on November 29th for the PS4 and Xbox One.